Walking lunges! Yes most of us hate them; but after you start seeing what they do for your legs and glutes your mind will be quickly changed! Great thing about them you can do them virtually anywhere and most all levels of fitness can benefit from them! My girlfriend and I recently did them while walking uphill at the Santa Barbara zoo.
Ways to challenge the lunges:
Add hand weights, about 10lbs
Add a barbell
Add a medicine ball with a torso twist
Finish the lunge off with a back leg lift (great for stability, glutes, and hamstrings)..see below
Front leg lift (stand all weight on forward leg and finish with extended the back leg in front of you; this challenges your core, glutes, and standing leg stability
So get up off the couch and walk to your next destination with lunges!